This invention relates to an improvement in web roll control mechanisms such as apparatus for unwinding a web such as disclosed in U.S. patent application Ser. No. 07/816,173, entitled WEB UNWINDING APPARATUS AND METHOD, filed Jan. 2, 1992, and now U.S. Pat. No. 5,209,418.
When unwinding a web from a web roll wound upon a core roll it is desirable to control the winding apparatus so as to slow down the unwinding operation especially when the web is about to run out and the web roll is therefor relatively small. At that juncture, due to the action of the looped belt moving in one direction, the web roll has a tendency to rock back and forth in such a way as to limit the usefulness of detectors utilizing horizontally disposed light beams and the like for controlling the speed of the unwinding. It is also possible that at some point, determined by web roll size, it may become desirable to reverse the belt let off and to wind a certain amount of the web so that accurately determining roll size becomes important.
While the web roll control and method hereof is described in connection with a belt let off of the type illustrated in U.S. patent application, Ser. No. 07/816,173, it may be desirable to utilize such in connection with determining the size of web rolls and the like in other configurations.